Flocking a Newtonian Reflector

[Jasonb]

Hi everyone,

I flocked the inside of my SkyWatcher 150P yesterday, with a roll of flocking material I got from FLO. It actually turned out to be an easier process than I thought, once I got over the fear of removing the mirrors from the tube!

As I had the mirrors out anyhow, I decided to also flock the back and sides of the Secondary Mirror and holder. This was harder due to the complex shapes/curves involved. I finally ended up with this...

 

Now I'm not too worried about the overlapping flocking material on the barrel of the mirror holder, as that's effectively not in the light path in my mind (as the back of the mirror is wider than the barrel) but I am curious about the overlapping flocking material on the edges of the mirror. It means that the edges are no longer perfectly smooth and uniform, and some bits (where it overlaps) are a little thicker/wider.

So, my question is this, will that overlapping material on the edges of the secondary cause any issues for me? I don't know, reducing light going down the tube (barely I guess), causing any observing issues etc.? I really don't know if it will or not, but I do know that when I was doing collimation I could see that the edges of the secondary were no longer smooth and uniform.

I'm pretty new to all this, so would appreciate any thoughts! Thanks!

[jetstream]

3 hours ago, Jasonb said:

will that overlapping material on the edges of the secondary cause any issues for me? I don't know,

Great job!

You are on the right path and the flocking wont bother the light throughput of your scope one bit. Your job will really enhance contrast and reduce the light blowing around the tube like newts do.

In my case I used a special paint to paint the interior of the tube and flocked opposite the focuser. The secondary edge is super important to do and I used paint. When you look down the tube, anything that appears shiny should be painted flat black, including the tops of the secondary adjustment screws.

Nice job, Gerry

[EarthLife]

1 hour ago, jetstream said:

In my case I used a special paint to paint the interior of the tube and flocked opposite the focuser. The secondary edge is super important to do and I used paint. When you look down the tube, anything that appears shiny should be painted flat black, including the tops of the secondary adjustment screws.

I wonder what "special paint" you use ?

I was thinking about using this "black hole" paint ..

https://www.stardustcolors.co.uk/bodywork-matt-paints-and-topcoats/1581-blackest-black-extreme-black-paint.html

Quite expensive but it's a one off thing to do.

Edited March 29, 2023 by EarthLife
typo

[Ratlet]

I doubt that the edges of the flock would have a significant impact on your views.  I guess in theory it could have an impact but whether you could see it.  You'll know when you have a look.  People run cables over the spider for dew heaters and the impact is negligible so a 0.5mm difference in the height of the edge isn't going to impact much I would say.

I used cheap blackboard paint from the local hardware store to do my secondary and it worked pretty well.  I'm not sure that there is much point using super expensive paints on it as with a large number of them whilst they might be perfectly black head on, at slight angles they aren't.  Flocking on the other hand is black from any direction.

Flocking is pretty easy you can either do the tube directly, or get a plastic poster cover (a la this: https://www.ebay.co.uk/itm/261693313857?hash=item3cee231341:g:~SIAAOSwAL9UhfqF&amdata=enc%3AAQAHAAAA4Kahr5AZ%2FYjD%2Fk9SSxRW4gaB%2FZo2NglX%2FfIfj%2F22dV8MkWbIulTmsi7RF3nGPn59sV1oQzyDkKrzDWiuEwIXWVuMSVDxVneIjZwg6tTt0J1GocuidSQMFUJYMa7vxxAuBxxtEKvlhaKfBZ2wsu2hti8eTZD39ab7gMrp%2FWii8kR4kOfoBDXhumvkEN4fys%2FJHGMPif00KYG39PzfslbB99z9Fe3bdYL%2FNdGpimeUySuX942VFgfPVdjiVmH1wPWY0Sbz%2F%2FfrgfnPXhWt8dh45T6kIUMVk7Ch1%2B4A8Gch69Bf|tkp%3ABFBMiPq_1-Vh) and cut it to fit the tube and holes first.  Then you lay the plastic out, stick the flock to the plastic and cut the holes out of the flock to match.  The whole lot slides in the tube and the tension of the plastic wanting to unroll keeps it to the tube (or you can use doublesided sticky tape for belt and braces.

 

Edited March 29, 2023 by Ratlet
changed wording so it reads like I can speak English

[Peter Drew]

I've never bothered to completely flock a tube but I have always flat blacked the secondary edge and any shiny part of the drawtube that projects inwards.  The most effective antireflection mod that I have found is to apply a flat back area on a white tube opposite to the eye not in use whilst observing.  This prevents a light area seen by this eye merging with the view of the observing eye.    🙂  

Edited March 29, 2023 by Peter Drew

[jetstream]

26 minutes ago, EarthLife said:

I what "special paint" you use ?

I'm in Canada and hate light blowing around the tube. I also do the focuser drawtube etc. This paint has actual smoke in it and was recommended by a retired chemist who now builds scopes. It works.

https://www.krylon.com/en/products/specialty/camouflage-paint#accordion-cee546f66e-item-9b5520e9a3

Edited March 29, 2023 by jetstream

[EarthLife]

7 minutes ago, jetstream said:

I'm in Canada and hate light blowing around the tube. I also do the focuser drawtube etc. This paint has actual smoke in it and was recommended by a retired chemist who now builds scopes. It works.

https://www.krylon.com/en/products/specialty/camouflage-paint#accordion-cee546f66e-item-9b5520e9a3

Amazing how they get that paint to create the camo effect

Amazon UK sell it it seems, though £74 a can ..

https://www.amazon.co.uk/Krylon-K02728007-Fusion-Spray-Paint/dp/B07LFRWLV8

[Jasonb]

Thanks for the replies, I think I'm safe with having some slight overlap and I don't think it's causing any light path issues...

[jetstream]

4 minutes ago, Jasonb said:

Thanks for the replies, I think I'm safe with having some slight overlap and I don't think it's causing any light path issues...

You did a great job and absolutely needed espc at f5. That overlap is of zero concern.

[Jasonb]

4 minutes ago, jetstream said:

You did a great job and absolutely needed espc at f5. That overlap is of zero concern.

Thanks! I did the whole of the inner tube as well...

[Planetarian]

Since you've flocked the tube, have you noticed lint from the flocking paper being collected on the mirror surfaces? I'm planning to flock mine, but a bit worried about residue.

[Spile]

7 hours ago, Planetarian said:

Since you've flocked the tube, have you noticed lint from the flocking paper being collected on the mirror surfaces? I'm planning to flock mine, but a bit worried about residue.

I did my OTA with black velour last year and there has been no shedding of material.

[Planetarian]

10 hours ago, Spile said:

I did my OTA with black velour last year and there has been no shedding of material.

Thanks, that's reassuring.

[Ricochet]

On 09/10/2023 at 13:58, Planetarian said:

Since you've flocked the tube, have you noticed lint from the flocking paper being collected on the mirror surfaces? I'm planning to flock mine, but a bit worried about residue.

Before you fit the flocking paper run a sticky lint roller over it to pick off any loose fibres. If you don't have a roller you can make a loop of sellotape with the sticky side on outside, and large enough to go around a few fingers, then roll it over the flocking. 

[Ratlet]

I hoovered mine before installation.

[Jasonb]

On 10/10/2023 at 17:21, Ricochet said:

Before you fit the flocking paper run a sticky lint roller over it to pick off any loose fibres. If you don't have a roller you can make a loop of sellotape with the sticky side on outside, and large enough to go around a few fingers, then roll it over the flocking. 

Yep, that's what I did, just to get rid of excess. It's not like it's falling off all over the place or anything like that, some stuff just comes loose as you're moving the material around. Once it's in place, it's no longer being manipulated, so I haven't had any issues with excess lint.